The present invention relates to a railway system with at least one track, and to a method for digital encoding of data for bidirectional transmission over the track.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Railway systems that detect the presence of track-bound vehicles on a track are known. The tracks are typically comprised of two rails, with the vehicles' wheels and axles that span the rails acting as a shunt between the rails. Railway signals for controlling movement of the railway cars are typically arranged proximate to the tracks. Safety devices are associated with the railway signals and exchange data on a secure data link for controlling the railway signals, whereby the data are exchanged bidirectionally over both rails of the track. For data exchange, digital electrical signals in form of signal pulses, in particular electrical current pulses, are transmitted over the two electrically conducting rails. This principle is also referred to as bidirectional encoded track circuit. Each of the data consists of one or more current pulses transmitted within a cycle time, which is divided into predetermined time intervals. U.S. Pat. No. 5,271,584 describes for example an exchange of data by means of signal pulses. Heretofore, conventional methods suffer shortcomings as data encoding has a relatively small encoding capacity.
It would therefore be desirable and advantageous to provide an improved system and method for encoding data for transmission over railway tracks, to obviate prior art shortcomings and to realize any increase in the encoding capacity, without adding complexity to the system.